Transcript Slide 1
Marisa Bernal
Neysa Alicea
Angélica Báez
Beatriz Ramos
if you loose any of your limbs?
Outline
Design
Purpose
Applications
Engineering Considerations
Uniqueness
Challenges
Areas of Opportunities
New Techniques
Prosthetic Leg
LINER
SOCKET
KNEE
FEET
Socket
Purpose
Improve the design of the prosthesis socket, making it
more comfortable for the user, and thus improving the
quality of life of people with disabilities.
Applications
For medical purposes, related to athletes with
disabilities.
Engineering Considerations
Use impact analysis in our calculations
Use the safest approximations for our design
Proper material selection
Material Characteristics
Lightweight low density
Stiff high Elastic Modulus
Minimize
Maximize
Material Characteristics
Material Characteristics
Material Possibilities
Wood
Technical Ceramics
Composites
Carbon Fiber Reinforced Plastics (CFRP)
Carbon Fiber Reinforced Plastic (CFRP)
Density: 1.8 g/cc
Modulus of Elasticity: 225 GPa
Sut: 3800 Mpa
Uniqueness
A prosthesis has to be designed to fit the needs of a
specific person.
It is customized for each user
Challenge
Consider that the product is a medical device
Convert our project to shapes that we can analyze with
the concept learned in class
Material Selection
Static Loads Analysis
Static Load Analysis
For this analysis we used the following equations and
obtained the shown values.
My
KN
115 .8 2
I
m
3V
KN
4.62 2
2A
m
qx3 C1 x 2
1
( x)
C 2 x C3
2
6
EI
(x )
2.68 x 10-6m= 2.6 x 10-3mm
Dynamic Load Analysis
Dynamic Load Analysis
Impact Load
Maximum Elongation
M=mass
v=velocity at impact
L=length
E=Elastic Modulus
A=area
Dynamic Load Analysis
Impact Load
Maximum stress
E = Elastic Modulus
δmax = maximum elongation
L = length
Dynamic Load Analysis
We calculated the values of:
= Pmean
amplitude = 128.69MPa = mean
Pamplitude =3195.38KN
Using stress concentrator factor Kf = 1.5
amplitude,SC = 192.95MPa
mean,SC = 192.95MPa
We calculated the fatigue strength:
'
S
f = 0.4 SUT
'
S f =1520MPa
Dynamic Load Analysis
Stress concentration factors:
K size 0.792
K load 0.85
K surface 0.7841
K termperature 1
K reliability 0.620
S f (0.792)(0.85)(0.7841)(1)(0.620)
S f 497.5MPa
Dynamic Load Analysis
Using Modified Goodman theory to calculate the
safety factor:
n
1
vm,a vm,m
S
S
f
UT
1
192.95MPa 192.95MPa
497.5MPa
3800MPa
2.28
Component life
Aproximated it to the behavior of aluminum
Sm
Sm
Sf
1.3 x 107
5 x 108
a=19922.54, b= -0.2815
N = 1.3 x 107 cycles
Areas of Opportunity
Assumed values were used since data for our material
was not available
Design uniqueness.
A different analysis is needed for each person
New Knowledge
Reinforce teamwork skills
Loads distribution in prosthetic devices
Impact loads
Any Questions???